Analysis of defects in thin SiO2thermally grown on Si substrate

Origin of defects in silicon dioxide thermally grown on silicon substrates has been studied. Breakdown characteristics of MOS capacitors with different gate areas were measured to examine the oxide defects. They strongly depend on the nature of silicon substrate, especially carbon and oxygen concentration in CZ silicon substrate. It is found that when the oxide is slightly etched by HF solution, an oxide defect becomes a pinhole defect. Assuming that oxygen precipitates in silicon substrate cause oxide defects, their density and size are estimated at 5-10×10⁶/cm³and 140-320 Å respectively. This model can explain the oxide dependence of breakdown failures and TDDB characteristic.